2018 Tundra, No ECM communication

Hey all, I am currently working on a 2018 Tundra with a 5.7. Originally came in with P0300 multi cylinder misfire, P0307 cylinder 7 misfire, P0101 Mass air flow sensor, and P2441 secondary air switching valve stuck bank one. I decided to go after the P2441 since in my eyes, this code could have started the other codes. I replaced the switching valves under the intake manifold as a pair. I cleared all codes, and test drove vehicle. it ran super smooth, not a single misfire, nothing. I parked the truck and turned it off. After I turned the truck off, I attempted to start it again, to check for any possible two trip codes. The truck has not started since I parked it after the first 2 mile test drive. The ecm has not communicated since, nor has the tcm.

I inspected some more things, found a couple wires had come out of the connector on the bank one switching valve. I wired in a new pig tail, and wired it as per alldata wiring diagram. all wires on bank one switching valve now have continuity. Fuses to the air switching valve drivers are good, and I am getting power to the drivers.

After all of this, I am still getting no communication, and I have code U0100 for lost communication with ECM/PCM A.

 

While not certain, I believe that it is the ecu that is responsible for communicating on the obd port. If you get U0100 it would seem to imply that the ecu and the canbus are alive. Possibly it means that the ecu has different modules internally that communicate and one is dead or a different module is not responding. The fact that it started once would seem to imply that it wasn’t something you did, but a guess. I would pull the battery and try again.

If the ecu decides that it wants to run sai at start up and you have fried the circuit in the switching valve this might explain it. If you reversed polarity or something this could have fried the circuit

no tcm on tundras

 

I have pulled the cables a couple of times, no change. I pulled the battery cables and zip tied them together to drain any residual charge from any modules, no change. U0100 code is stored in Instrument Panel and in Navigation system, both stating no communication to "ECM A". During code scan, missing Engine and Transmission modules. I have pinned out ECM battery power and ignition power, I am getting those, currently checking grounds.

I am just at a loss as to why it could run fine for a 2 mile test drive, get parked, and now no communication. I feel like I'm missing something obvious.

 

If the scanner says it cannot communicate with the ecu, that pretty well provides a solid lead that the ecu is not healthy. Can’t say why it happened now, but if it is getting power but not talking, good chance it has a problem. Last thing to check is to find the two can bus wires on the ecu connector and check for the 60 or 120 ohms. If they are open, it could be you hit the canbus wires. If the ecu doesn’t have a can bus connection, I assume it will not start.